Substrate processing apparatus

ABSTRACT

A method of manufacturing a semiconductor device includes conveying a first substrate provided with an opposing surface having insulator regions and a semiconductor region exposed between the insulator regions and a second substrate provided with an insulator surface exposed toward the opposing surface of the first substrate, into a process chamber in a state that the second substrate is arranged in to face the opposing surface of the first substrate, and selectively forming a silicon-containing film with a flat surface at least on the semiconductor region of the opposing surface of the first substrate by heating an inside of the process chamber and supplying at least a silicon-containing gas and a chlorine-containing gas into the process chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/178,232 filed on Jul. 7, 2011, which claims the benefit of priorityfrom Japanese Patent Application No. 2010-155937, filed on Jul. 8, 2010,the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method of manufacturing asemiconductor device and a substrate processing apparatus.

BACKGROUND

A substrate such as a silicon (Si) wafer may have a semiconductor regionexposed between insulator regions, on which an epitaxial film of silicon(Si) or silicon germanium (SiGe) is formed by selective growth. In thecase where the selective growth of an epitaxial film is implementedusing a substrate processing apparatus, e.g., a hot-wall type CVDapparatus, a substrate such as a silicon (Si) wafer is first loaded intoa reaction furnace and then the reaction furnace is heated or cooled toa target film-forming temperature. After the reaction furnace hasreached the target film-forming temperature, it takes a certain amountof stabilization time sufficient to stabilize the internal temperatureof the reaction furnace and the temperature of the inside of the wafersurface. Thereafter, a source gas is supplied to the reaction furnaceand an epitaxial film of silicon (Si) or silicon germanium (SiGe) isformed by selective growth.

Conventionally, to reliably perform selective growth, the rear surface(opposing surface) of a substrate arranged immediately above afilm-forming target substrate is made of a silicon (Si)-based material.Referring to Japanese Patent Laid-Open Publication No. HeiS-206040, forexample, the rear surface of a substrate is made of a silicon (Si)-basedmaterial such as polysilicon (poly-Si). In this case, prior toperforming selective growth of a silicon (Si) film or a silicongermanium (SiGe) film, the silicon (Si) on the rear surface of thesubstrate is exposed by wet-cleaning or dry-cleaning the substrate inthe course of a substrate manufacturing step in which a natural oxidefilm is removed from the substrate. Thereafter, an epitaxial film isformed by selective growth.

Further, Japanese Patent No. 4394120 discloses a method without exposingsilicon (Si) on the rear surface (opposing surface) of a substrate,where dummy substrates are charged into a boat at a pitch twice as greatas a normal pitch and the boat is loaded into a reaction furnace to formpolysilicon (poly-Si) films on the dummy substrates in advance. Aproduct substrate is inserted between the dummy substrates having thepolysilicon (poly-Si) films formed thereon. Then, the boat is loadedinto the reaction furnace once again to perform selective growth of anepitaxial film.

In the aforementioned related art in which the opposing surface of asubstrate is made of silicon (Si) or polysilicon (poly-Si), however, asilicon (Si)-containing film tends to obtain a stable shape when thesilicon (Si)-containing film is formed on a semiconductor region of asubstrate exposed between insulator regions. This may cause themigration of silicon (Si), and as a result, the shape of the silicon(Si)-containing film becomes uneven and sometimes becomes round. Thisproblem is particularly conspicuous when performing selective growth ofa thin silicon (Si) film or a thin silicon germanium (SiGe) film havinga thickness of about 100 Å.

SUMMARY

The present disclosure provides some embodiments of a method ofmanufacturing a semiconductor device and a substrate processingapparatus, which are capable of selectively forming a silicon-containingfilm with a flat surface on a semiconductor region of a substrate.

According to one embodiment of the present disclosure, there is provideda method of manufacturing a semiconductor device, including: conveying afirst substrate provided with an opposing surface having insulatorregions and a semiconductor region exposed between the insulator regionsand a second substrate provided with an insulator surface exposed towardthe opposing surface of the first substrate, into a process chamber in astate that the second substrate is arranged to face the opposing surfaceof the first substrate; and a second step of selectively forming asilicon-containing film with a flat surface at least on thesemiconductor region of the opposing surface of the first substrate byheating an inside of the process chamber and supplying at least asilicon-containing gas and a chlorine-containing gas into the processchamber.

According to another embodiment of the present disclosure, there isprovided a method of manufacturing a semiconductor device, including:providing a plurality of substrates each provided with a front surfaceand a rear surface, the front surface having insulator regions and asemiconductor region arranged between the insulator regions, at leastthe semiconductor region of the front surface being covered with anoxide film, the rear surface being covered with an oxide film; removingthe oxide film formed on the semiconductor region of the front surfacewhile keeping intact the oxide film formed on the rear surface;conveying the substrates, in which the oxide film formed on thesemiconductor region is removed with the oxide film formed on the rearsurface remaining intact, into a process chamber in a state that thesubstrates are stacked one above another at a predetermined interval;and selectively forming a silicon-containing film on the semiconductorregion of each of the substrates by heating the process chamber andsupplying at least a silicon-containing gas and a chlorine-containinggas into the process chamber.

According to still another embodiment of the present disclosure, thereis provided a substrate processing apparatus, including: a processchamber configured to accommodate and process a first substrate providedwith an opposing surface having insulator regions and a semiconductorregion exposed between the insulator regions and a second substrateprovided with an insulator surface exposed toward the opposing surfaceof the first substrate; a first gas supply system configured to supply asilicon-containing gas into the process chamber; a second gas supplysystem configured to supply a chlorine-containing gas into the processchamber; a heater configured to heat the first substrate and the secondsubstrate; and a controller configured to control the heater, the firstgas supply system and the second gas supply system such that thesilicon-containing gas and the chlorine-containing gas are suppliedbetween the first substrate and the second substrate, the secondsubstrate arranged to face the opposing surface of the first substrate,to selectively form a silicon-containing film with a flat surface atleast on the semiconductor region of the first substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic overall view showing a vertical low-pressure CVDapparatus according to a first embodiment of the present disclosure.

FIG. 2 is a schematic view showing a reaction furnace according to thefirst embodiment.

FIG. 3 is a schematic vertical section view of a boat in which a wafertransfer operation is performed, and dummy wafers each having an exposedinsulator surface are placed immediately above product wafers, accordingto a second embodiment of the present disclosure.

FIGS. 4A and 4B are schematic views showing different gas reactionsaccording to the first embodiment, which depends on a difference in thetype of an opposing surface.

FIGS. 5A and 5B are schematic views showing different epitaxial filmsaccording to the first embodiment, which depends on a difference in thetype of an opposing surface.

FIGS. 6A, 6B and 6C are views showing an oxide film removal process forremoving an oxide film formed on the front surface of a wafer and forremoving an oxide film formed on the rear surface of a wafer accordingto the second embodiment.

FIG. 7 is a section view showing a substrate cleaning apparatus forimplementing the oxide film removal process according to the secondembodiment.

FIG. 8 is a schematic overall view showing a batch-type low-pressure CVDapparatus according to a third embodiment of the present disclosure.

FIG. 9 is a schematic vertical section view of a MOSFET structure havinga typical elevated source/drain.

DETAILED DESCRIPTION

As mentioned above, the migration of silicon (Si) may easily occur andthus the shape of a silicon-containing film becomes uneven, according tothe related art method in which a silicon-containing film is allowed toselectively grow on a semiconductor region of a substrate which isprovided so that another substrate exposes a silicon-based film formedon a surface oppo sing thereto. According to one embodiment of thepresent disclosure, a surface of a second substrate opposing a firstsubstrate is formed of an insulator surface. A silicon (Si)-containinggas and a chlorine (Cl)-containing gas are supplied into a reactionchamber. If the surface of the second substrate opposing to the firstsubstrate is formed of the insulator surface, the migration of silicon(Si) is suppressed by the chlorine components contained in the chlorine(Cl)-containing gas. This makes it possible to selectively form, withinthe reaction chamber, a silicon-containing film with a flat surface on asemiconductor region of the first substrate in a reliable manner.

[Method of Manufacturing a Semiconductor Device]

Hereinafter, certain embodiments of a method of manufacturing asemiconductor device will be described in detail.

One Embodiment

A method of manufacturing a semiconductor device according to oneembodiment of the present disclosure includes: providing a firstsubstrate provided with an opposing surface having insulator regions anda semiconductor region exposed between the insulator regions and asecond substrate provided with an insulator surface exposed toward theopposing surface of the first substrate; arranging the second substrateto face the opposing surface of the first substrate; and selectivelyforming a silicon-containing film with a flat surface at least on thesemiconductor region of the first substrate by supplying asilicon-containing gas and a chlorine-containing gas to at least betweenthe first substrate and the second substrate.

The insulator regions of the first substrate are exposed. Thesemiconductor region of the first substrate is exposed between theinsulator regions. The second substrate is arranged to face the firstsubstrate. The insulator surface of the second substrate is exposedtoward the opposing surface of the first substrate. The first substrateand the second substrate are, e.g., silicon (Si) wafers. The insulatorregions of the first substrate and the insulator surface of the secondsubstrate are made of, e.g., a silicon oxide (SiO) material or a siliconnitride (SiN) material. The semiconductor region of the first substrateis made of, e.g., a silicon (Si) material.

The silicon-containing film is, e.g., an epitaxial film of silicon (Si)or silicon germanium (SiGe). The silicon-containing film may be formedat least on the first substrate. Alternatively, the silicon-containingfilm may be formed not only on the first substrate but also on thesecond substrate. In this case, similar to the first substrate, thesilicon-containing film of the second substrate is selectively formed ona semiconductor region thereof. The first substrate and the secondsubstrate may be different ones or may be identical with each other.

In case where the silicon-containing film to be formed is a silicon (Si)film, the silicon (Si)-containing gas may be, e.g., a silane (SiH₄) gas,a disilane (Si₂H₆) gas or a dichlorosilane (SiH₂Cl₂) gas. The chlorine(Cl)-containing gas may be, e.g., a chlorine (Cl₂) gas or a hydrogenchloride (HCl) gas which differs from the silicon (Si)-containing gas.In addition, a diluent gas (e.g., a H₂ gas) may be supplied between thefirst substrate and the second substrate. In case where thesilicon-containing film to be formed is a silicon germanium (SiGe) film,the silicon (Si)-containing gas is added with germane (GeH₄).

According to the method of the present embodiment, if a silicon(Si)-containing gas and a chlorine (Cl)-containing gas are suppliedbetween the first substrate and the second substrate, chlorine (Cl)components exhibiting increased surface coverage are chlorine(Cl)-terminated in a growth region, namely in the semiconductor regionof the first substrate. This is because the second substrate having aninsulator film on its surface opposing to the first substrate isarranged to face the first substrate. Thus, the migration of silicon(Si) is suppressed, which makes it possible to selectively form asilicon (Si)-containing film with a flat surface at least on thesemiconductor region of the first substrate in a reliable manner.

Another Embodiment

A method of manufacturing a semiconductor device according to anotherembodiment of the present disclosure includes first and second steps offorming a silicon (Si)-containing film. The first step is configured toconvey a first substrate provided with an opposing surface havinginsulator regions and a semiconductor region exposed between theinsulator regions and a second substrate provided with an insulatorsurface exposed toward the opposing surface of the first substrate, intoa reaction chamber in a state that the second substrate is arranged toface the opposing surface of the first substrate. The second step isconfigured to selectively form a silicon-containing film with a flatsurface at least on the semiconductor region of the opposing surface ofthe first substrate by heating the inside of the reaction chamber andsupplying at least a silicon-containing gas and a chlorine-containinggas into the reaction chamber.

The silicon-containing film is, e.g., an epitaxial film of silicon (Si)or silicon germanium (SiGe). The silicon-containing film may be formedat least on the first substrate, more particularly on the semiconductorregion of the first substrate. Accordingly, a dummy substrate having aninsulator surface exposed toward the opposing surface of the firstsubstrate can be used as the second substrate, and a product substratehaving insulator regions and a semiconductor region exposed between theinsulator regions can be used as the first substrate. In one embodiment,the silicon-containing film may be formed not only on the firstsubstrate but also on a semiconductor region of the second substrate. Inthis case, identical product substrates can be used as the firstsubstrate and the second substrate. The product substrate may refer to asubstrate from which semiconductor devices such as ICs are actuallymanufactured. The dummy substrate may refer to a substrate used toprevent deterioration of film formation. For this purpose, two dummysubstrates are arranged above and below the product substrate so thatthe product substrate can be interposed therebetween.

According to the method of the present embodiment, if a silicon(Si)-containing gas and a chlorine (Cl)-containing gas are supplied intoa heated reaction chamber, chlorine (Cl) components exhibiting increasedsurface coverage are chlorine (Cl)-terminated at least in a growthregion, namely in the semiconductor region of the first substrate. Thisis because the second substrate having an insulator film on its surfaceopposing to the first substrate is arranged to face the first substrate.Thus, the migration of silicon (Si) is suppressed, which makes itpossible to selectively form a silicon (Si)-containing film with a flatsurface at least on the semiconductor region of the first substrate in areliable manner.

In the second step mentioned above, a material formed by decompositionof the silicon-containing gas and the chlorine-containing gas in agaseous layer within the reaction chamber may be adsorbed to at leastthe rear surface of the second substrate and the semiconductor region ofthe first substrate. In this regard, the gases decomposed in the gaseouslayer within the reaction chamber may be, e.g., a silane (SiH₄) gas, adisilane (Si₂H₆) gas, a dichlorosilane (SiH₂Cl₂) gas or a germane (GeH₄)gas. The material formed by decomposition of the silicon-containing gasand the chlorine-containing gas in the gaseous layer within the reactionchamber may be, e.g., silicon (Si) or silicon germanium (SiGe).

Since the material formed by decomposition is adsorbed to the rearsurface of the second substrate and the semiconductor region of thefirst substrate, it is possible to selectively form a silicon-containingfilm with a flat surface on the semiconductor region of the firstsubstrate in a reliable manner.

Further Embodiment

While the silicon (Si)-containing film is formed at least on the firstsubstrate in the embodiments described above, an additional silicon(Si)-containing film may be formed on the second substrate. In thiscase, the second substrate is configured such that a semiconductorregion is exposed between insulator regions on the opposite surface ofthe second substrate from the opposing surface of the first substrate.This makes it possible to selectively form a silicon-containing filmwith a flat surface even on the semiconductor region of the secondsubstrate in a reliable manner.

Still Further Embodiment

While the silicon (Si)-containing film is formed on the first substrateor the second substrate in the embodiments described above, the firstsubstrate and the second substrate may be identical with each other anda plurality of identical substrates may be conveyed into a reactionchamber to form silicon (Si)-containing films on the respectivesubstrates.

To this end, the method of manufacturing a semiconductor deviceaccording to the present embodiment may include: providing a pluralityof substrates, the front surface of the ea ch substrates havinginsulator regions and a semiconductor region arranged between theinsulator regions, at least the semiconductor region of the frontsurface being covered with an oxide film, the rear surface of the eachsubstrates being covered with an oxide film; removing the oxide filmformed on the semiconductor region of the front surface of each of thesubstrates while keeping intact the oxide film formed on the rearsurface of each of the substrates; and conveying the substrates, inwhich the oxide film formed on the semiconductor region is removed whilethe oxide film formed on the rear surface remaining intact, into areaction chamber in a state that the substrates are stacked one aboveanother at a predetermined interval.

According to this method, the substrates in which the oxide film formedon the rear surface remains intact can be stacked one above another.This makes it possible to simultaneously form, within the reactionchamber, silicon-containing films on the semiconductor regions of aplurality of substrates in a reliable manner.

Yet Still Further Embodiment

A substrate holder can be used to convey a plurality of stackedsubstrates into a reaction chamber. To this end, in the presentembodiment, a substrate holder holding the substrates vertically stackedone above another at a predetermined interval may be conveyed into thereaction chamber in the conveying step mentioned above, each of thesubstrates provided with a front surface having insulator regions and asemiconductor region exposed between the insulator regions and a rearsurface formed of an exposed insulator surface. According to thismethod, silicon-containing films are formed on the semiconductor regionsof the substrates held by the substrate holder within the reactionchamber. This makes it possible to process an increased number ofsubstrates that can be conveyed by the substrate holder, thereby greatlyenhancing the throughput.

In one embodiment, the insulator regions and the semiconductor regionmay be formed at different heights. If the insulator regions aresubstantially flush with the semiconductor region, the silicon(Si)-containing layers selectively formed on the semiconductor regioncan have a flat surface.

[Substrate Processing Apparatus]

A substrate processing apparatus for implementing one process of theabove-described semiconductor device manufacturing method is configuredas follows.

One Embodiment

A substrate processing apparatus according to one embodiment of thepresent disclosure includes a reaction chamber, a first gas supplysystem, a second gas supply system, a heater and a controller.

The reaction chamber is defined within a process vessel. A firstsubstrate and a second substrate are arranged to be processed within thereaction chamber. The first gas supply system serves to supply asilicon-containing gas into the reaction chamber. The second gas supplysystem serves to supply a chlorine-containing gas into the reactionchamber. The heater serves to heat the substrates to a processingtemperature. The heater is configured by, e.g., a resistance heater.

The controller is configured to control the heater, the first gas supplysystem and the second gas supply system such that a silicon-containinggas and a chlorine-containing gas are supplied between a firstsubstrate, which is provided with an opposing surface having insulatorregions and a semiconductor region exposed between the insulatorregions, and a second substrate, which is provided with an exposedinsulator surface and arranged in an opposing relationship with theopposing surface of the first substrate, to selectively form asilicon-containing film with a flat surface on the semiconductor regionof the first substrate.

With this configuration, the first substrate and the second substratearranged within the reaction chamber are heated by the heater controlledby the controller. If the silicon-containing gas and thechlorine-containing gas are supplied between the first substrate and thesecond substrate by the first gas supply system and the second gassupply system under the control of the controller, chlorine componentsexhibiting increased surface coverage are chlorine (Cl)-terminated in agrowth region, namely in the semiconductor region of the firstsubstrate. Thus, the migration of silicon (Si) is suppressed, whichmakes it possible to selectively form a silicon (Si)-containing filmwith a flat surface at least on the semiconductor region of the firstsubstrate in a reliable manner.

Specific Example

The substrate processing apparatus according to one embodiment of thepresent disclosure will be described in detail with reference to theaccompanying drawings.

FIG. 1 is a schematic vertical section view showing a hot-wall typevertical low-pressure CVD apparatus, one specific example of thesubstrate processing apparatus for implementing one process of thesemiconductor device manufacturing method according to the presentembodiment. FIG. 2 is a schematic vertical section view showing areaction furnace employed in the hot-wall type vertical low-pressure CVDapparatus according to the present embodiment.

(Hot-Wall Type Vertical Low-Pressure CVD Apparatus)

As shown in FIG. 1, the hot-wall type vertical low-pressure CVDapparatus 180 according to the present embodiment includes a reactionfurnace 100, a control device 141 (used as a controller), a gas supplydevice 142 and a vacuum exhaust device 143. The reaction furnace 100includes a reaction vessel 104, a heater 101 provided outside thereaction vessel 104 and an insulating material 102 provided to cover theheater 101 and the reaction vessel 104.

An exhaust pipe 116 is attached to the sidewall of the reaction vessel104 and is connected to the vacuum exhaust device 143. A nozzle 108 isprovided to pass through the reaction vessel 104. A supply pipe 115connected to the nozzle 108 is provided outside the reaction vessel 104.The supply pipe 115 is connected to the gas supply device 142. A sourcegas for selective growth of a Si film or a SiGe film is supplied to thenozzle 108 through the supply pipe 115 and is introduced into thereaction vessel 104 from the nozzle 108. The gas introduced into thereaction vessel 104 is exhausted from the exhaust pipe 116 by the vacuumexhaust device 143.

A boat 105 (used as a substrate holder) is loaded into and unloaded fromthe reaction vessel 104. If the boat 105 is lifted up and loaded intothe reaction vessel 104, the furnace opening of the reaction vessel 104is closed. If the boat 105 is lowered down and unloaded from thereaction vessel 104, the furnace opening is closed by a gate valve 117.A transfer machine 151 is provided for transferring wafers 130 betweenthe boat 105 (which is unloaded from the reaction furnace 100) and awafer cassette 152 accommodating the wafers 130.

(Reaction Furnace)

The detailed configuration of the reaction furnace 100 is shown in FIG.2. The reaction furnace 100 includes a base 112, a manifold 111 providedabove the base 112, a reaction tube 103 and a heater 101 providedoutside the reaction tube 103. A reaction chamber 109 is defined withinthe reaction tube 103. The entire inside of the reaction tube 103 isheated by the heater 101. The reaction tube 103 is provided on an upperflange 118 of the manifold 111. The reaction vessel 104 mentioned aboveis configured by the reaction tube 103 and the manifold 111.

The heater 101 for heating the reaction tube 103 are divided into fiveelements, e.g., a top heater 101 a, a central upper heater 101 b, acenter heater 101 c, a central lower heater 101 d and a bottom heater101 e. The internal temperature of the reaction furnace 100 iscontrolled by the control device 141. Alternatively, the heater 101 maynot be divided but provided as one integrated body.

The boat 105 is placed on a seal cap 113. The boat 105 held by the sealcap 113 is loaded through the opening 120 of the base 112. The opening120 is configured to be closed by the seal cap 113 as the seal cap 113moves upward. When the opening 120 is closed, the boat 105 is positionedwithin the reaction tube 103. The boat 105 is rotated by a rotationmechanism 114. The wafers 130 are vertically stacked one above anotherin the boat 105. The inside of the reaction tube 103 serves as thereaction chamber 109 within which the wafers 130 are subjected toprocessing. Heat shield panels 107 are arranged in the lower portion ofthe boat 105 at a height corresponding to the height of the manifold111. Once the seal cap 113 is moved down and the boat 105 is unloadedfrom the reaction vessel 104, the opening 120 of the base 112 is closedby the gate valve 117 (see FIG. 1).

First and second nozzles 108 a and 108 b are provided within thereaction vessel 104 along the boat 105. The first and second nozzles 108a and 108 b are inserted into the reaction tube 103 from the lowerportion of the manifold 111. The first nozzle 108 a composes a first gassupply system for supplying a silicon-containing gas. The second nozzle108 b composes a second gas supply system for supplying achlorine-containing gas. A nozzle for supplying a carrier gastherethrough is also provided but is not shown for simplicity. Anexhaust pipe 116 is attached to the sidewall of the manifold 111.

For the selective growth of a film of silicon (Si) or silicon germanium(SiGe), a silicon (Si)-containing gas as a source gas is introduced fromthe first nozzle 108 a. In case of selective growth of a silicon(Si)-containing film, the silicon (Si)-containing gas may be, e.g., asilane (SiH₂) gas, a disilane (Si₂H₆) gas or a dichlorosilane (SiH₂Cl₂)gas. In case of selective growth of a silicon germanium(SiGe)-containing film, the silicon (Si)-containing gas is added with agermanium (Ge) such as germane (GeH₄).

In addition to the silicon (Si)-containing gas and the germanium(Ge)-containing gas, a chlorine (Cl)-containing gas is introduced fromthe second nozzle 108 b to assure increased selectivity. A chlorine(Cl₂) gas or a hydrogen chloride (HCl) gas may be used as the chlorine(Cl)-containing gas.

The source gas introduced into the top portion of the reaction tube 103from the first nozzle 108 a or the second nozzle 108 b flows down withinthe reaction tube 103 past the wafers 130 as substrates stacked oneabove another. Then, the source gas is exhausted from the exhaust pipe116 arranged in the lower portion of the reaction tube 103.

A temperature control unit configured to control the heater 101, a gasflow rate control unit configured to control the gas supply device 142,a pressure control unit configured to control the vacuum exhaust device143 and a drive control unit configured to control the rotationmechanism 114, the gate valve 117 and the transfer machine 151 areelectrically connected to a main control unit configured to control theentire operation of the hot-wall type vertical low-pressure CVDapparatus 180. The temperature control unit, the gas flow rate controlunit, the pressure control unit and the drive control unit configure acontroller 141.

In the hot-wall type vertical low-pressure CVD apparatus 180 describedabove, the wafers (Si substrates) 130 held in the wafer cassette 152 aretransferred from the wafer cassette 152 to the boat 105 by the transfermachine 151. If all the wafers 130 are completely transferred, the boat105 is loaded into the reaction vessel 104. The inside of the reactionvessel 104 is depressurized by the vacuum exhaust device 143. Then, thewafers 130 are heated by the heater 101 to a desired temperature, e.g.,400° C. or less. If the temperature becomes stable, a source gas issupplied by the gas supply device 142 through the supply pipe 115 andthe nozzle 108. As a result, a CVD reaction is caused to occur so that asilicon (Si) film or a silicon germanium (SiGe) film as a semiconductorfilm with a flat surface can grow on each of the wafers (Si substrates)130 in a reliable manner.

The following is a description on a first embodiment of a mechanism bywhich a silicon (Si)-containing film with a flat surface is selectivelyformed on the semiconductor region of the first substrate, withreference to the accompanying drawings.

First Embodiment

This embodiment is related to a case in which a product Si wafer is usedas a first substrate and a dummy Si wafer differing from the product Siwafer is used as a second substrate.

FIG. 3 is a schematic explanation view showing a boat according to oneembodiment of the present disclosure and a transfer machine configuredto transfer a plurality of wafers to and from the boat. The boat 105unloaded from the reaction furnace waits below the reaction furnace. Thetransfer machine 151 is provided adjacent to the boat 105. The transfermachine 151 is configured to hold a plurality of, e.g., five, wafers 130with a corresponding number of tweezers 133 and transfer them to theboat 105 at one time.

The wafers 130 include product Si wafers 131 and dummy Si wafers 132.The product Si wafers 131 may refer to wafers from which semiconductordevices such as ICs are actually manufactured. The dummy Si wafers 132,which differ from the product Si wafers 131, are arranged above andbelow the respective product Si wafers 131 so that the product Si wafers131 can be interposed between the dummy Si wafers 132. The dummy Siwafers 132 serve to prevent heat from dissipating from around theproduct Si wafers 131 and prevent fine particles or contaminantsscattering around the product Si wafers 131 from adhering thereto. Thedummy Si wafers 132 may refer to wafers for preventing deterioration offilm formation which may be caused by turbulent gas flow or uneventemperature distribution. In FIG. 3, the dummy Si wafers 132 arevertically stacked one above another in the boat 105. The respectiveproduct Si wafers 131 transferred by the transfer machine 151 areinserted and arranged between the corresponding upper and lower dummy Siwafers 132. As a result, each of the dummy Si wafers 132 provided withan exposed insulator surface is arranged immediately above acorresponding one of the product Si wafers 131. The dummy Si wafersmentioned above are often referred to as sandwiching dummy wafersbecause they are configured to sandwich the product Si wafers.

In this embodiment, the product Si wafers 131 are silicon (Si) waferseach provided with a front surface (major surface) having asemiconductor silicon (Si) region to be subjected to selective growth.The semiconductor silicon (Si) region is formed between insulatorregions made of silicon oxide (SiO₂) or silicon nitride (SiN). Therespective dummy Si wafers 132 are arranged in a parallel to face themajor surfaces of the corresponding product Si wafers 131 to besubjected to selective growth. Dummy silicon (Si) wafers each having anitride film (a SiN film or a Si₃N₄ film) exposed at least on the rearsurface thereof are prepared as the dummy Si wafers 132.

In one process of a semiconductor device manufacturing method to form asilicon (Si)-containing film, at least one product Si wafer and at leastone dummy Si wafer having a SiN film (or a Si₃N₄ film) exposed at leaston the rear surface thereof are accommodated within a reaction chamberin such a state that the rear surface of the dummy Si wafer is arrangedto face the surface of the product Si wafer to be subjected to selectivegrowth.

Next, the product Si wafer and the dummy Si wafer accommodated withinthe reaction chamber are heated by a heater arranged outside thereaction chamber. Concurrently, a process gas is supplied into thereaction chamber from a process gas supply system while exhausting theprocess gas out of the reaction chamber. At this time, a material formedby decomposition of the process gas in a gaseous layer within thereaction chamber is adsorbed to the SiN film (or the Si₃N₄ film) on therear surface of the dummy Si wafer and also to the Si region of theproduct Si wafer, thereby allowing a Si-containing film to selectivelygrow on the Si region.

In case of selective growth of Si or SiGe, the selectively growingsilicon (Si)-containing film may be, e.g., an elevated source/drain of aMOSFET.

FIG. 9 is a schematic vertical section view showing a MOSFET 310 havingan elevated source/drain formed thereon. On a device-forming siliconregion 311 surrounded by a device isolation region 312, a gate electrode320 is formed through a gate insulation film 317. A sidewall 318 isformed on the side surface of the gate electrode 320. A gate protectionfilm 319 is formed on the top surface of the gate electrode 320. In thedevice-forming silicon region 311, a source 313 and a drain 314 areformed in a self-aligning manner with respect to the gate electrode 320.An elevated source 315 and an elevated drain 316 are selectively formedonly on the source 313 and the drain 314. The elevated source 315 andthe elevated drain 316 are formed by a technique generally referred toas selective growth, in which Si or SiGe is allowed to epitaxially growonly on the source 313 and the drain 314 exposing Si while any materialis not allowed to grow on the device isolation region 312 exposing SiO₂or SiN.

In case where a silicon (Si)-containing film such as an elevated sourceor an elevated drain is allowed to selectively grow on the silicon (Si)region at a relatively great thickness, the degree of selective growthdepends largely on whether the opposing surface (e.g., a substratesurface opposing the selectively grown film) is a silicon-based film oran insulator-based film.

FIGS. 4A and 4B are schematic views showing different gas reactions incase where the opposing surface is formed of a silicon (Si)-basedmaterial such as polysilicon (poly-Si) or the like (FIG. 4A) and in casewhere the opposing surface is formed of an insulator-based material suchas SiN or SiO₂ (FIG. 4B). If a silicon (Si)-containing film such as anelevated source/drain or an embedded source/drain needs to have athickness of, e.g., 500 Å or more in the selective growth of Si or SiGe,the surface of the dummy Si wafer 132 a opposing the product Si wafer131 is made of a silicon (Si)-based material such as polysilicon(poly-Si) or the like as shown in FIG. 4A. This enables active species(e.g., SiH₄) to be adsorbed to the opposing surface of the product Siwafer 131, which makes it possible to maintain selectivity. On the otherhand, if the surface of the dummy Si wafer 132 b opposing the product Siwafer 131 is made of an insulator-based material such as SiN or SiO₂(FIG. 4B), it is highly probable that a reaction with silicon nitride(SiN) or silicon oxide (SiO₂) occurs above the product Si wafer. Thisshortens a latent period, which prevents the selective growth or thethickness of a film that can be formed by the selective growth becomesextremely small.

In contrast, when the selective growth of silicon (Si) or silicongermanium (SiGe) is performed to form a thin film, an insulator-basedfilm of silicon nitride (SiN) or silicon oxide (SiO₂) may be exposed onthe surface of the dummy Si wafer opposing the product Si wafer. Forexample, when a silicon (Si)-containing film is caused to grow on thesemiconductor region of the product Si wafer exposed between theinsulator regions to have a height greater than the height of theinsulator regions, the migration of silicon (Si) is suppressed even ifthe selective growth of silicon (Si) or silicon germanium (SiGe) isperformed to form a thin film of, e.g., about 100 Å. Therefore, if thesurface of the dummy Si wafer opposing the product Si wafer is made ofsilicon nitride (SiN) or silicon oxide (SiO₂) and if asilicon-containing gas and a chlorine-containing gas are supplied intothe reaction chamber, it becomes possible to form a flat epitaxial filmin a reliable manner.

The above process will be described in more detail with reference toFIG. 5. The source gas used in this example is a silane (SiH₄) gas addedwith a germane (GeH₄) gas and a hydrogen chloride (HCl) gas. Under theepitaxial growth conditions of predetermined temperature, pressure andflow rate, the source gas is thermally decomposed on the semiconductorregion (silicon (Si) region) of the product Si wafer, therebyepitaxially and selectively growing a monocrystalline film of silicongermanium (SiGe) only on the silicon (Si) region.

As shown in FIG. 5A, if the surface of the dummy Si wafer 132 a opposingthe product Si wafer 131 is made of a silicon (Si)-based material suchas polysilicon (poly-Si) or the like, a SiGe epitaxial film 165 formedon the silicon (Si)-made semiconductor region 161 of the product Siwafer 131 (which is exposed between the insulator regions 163 made ofsilicon oxide (SiO₂) or silicon nitride (SiN)) may not be maintained tobe flat, but become a round shape (e.g., a bulging or convex shape).This is because the Cl components of a source gas, e.g., a silane (SiH₄)gas, are consumed not only by the semiconductor region 161, i.e., thegrowth surface, of the product Si wafer 131 but also by the rear surfaceof the dummy Si wafer 132 a positioned above the semiconductor region161, consequently accelerating the migration of silicon (Si) andreducing the surface coverage of the Cl components on the product Siwafer 131.

In contrast, as shown in FIG. 5B, if the surface of the dummy Si waferopposing the product Si wafer 131 is made of an insulator-based film ofsilicon nitride (SiN) or silicon oxide (SiO₂), a flat SiGe epitaxialfilm 166 is formed on the silicon (Si)-made semiconductor region 161 ofthe product Si wafer 131 exposed between the insulator regions 163 madeof silicon oxide (SiO₂) or silicon nitride (SiN). This is because the Clcomponents of silane (SiH₄) are sufficiently supplied onto the productSi wafer 131. For this reason, the Cl components with increase surfacecoverage are Cl-terminated on the growth region of the product Si wafer131 during the selective growth of silicon (Si) or silicon germanium(SiGe), thereby suppressing the migration of silicon (Si). TheCl-terminated Cl components are substituted by active species such assilane (SiH₄) or germane (GeH₄), which eliminates the possibility thatthe Cl components remain in the film. According to the above process,the surface of the dummy Si wafer facing the product Si wafer is formedof an insulation film, thereby improving the flatness of the film formedon the semiconductor region of the product Si wafer.

Although germanium (Ge) is used as a source material in the exampleshown in FIGS. 5A and 5B, silicon (Si) may be used instead of germanium(Ge). In this case, germanium (Ge) in the plan crystal structure diagramshown in FIGS. 5A and 5B may be replaced by silicon (Si). With thisarrangement, a silicon (Si) epitaxial film may be formed instead of thesilicon germanium (SiGe) epitaxial film formed in the above example.

(Process Conditions)

In the first embodiment described above, the process conditions for theselective growth of silicon (Si) or silicon germanium (SiGe) may be setas follows. For example, the flow rate of the silicon (Si)-containinggas may be in a range of from 50 sccm to 1,000 sccm, the flow rate ofthe germanium (Ge)-containing gas may be in a range of from 0 sccm to500 sccm, the flow rate of the chlorine (Cl)-containing gas may be in arange of from 10 sccm to 200 sccm, the flow rate of the hydrogen (H₂)gas may be in a range of from 0 slm to 20 slm, the internal temperatureof the reaction chamber may be in a range of from 450° C. to 700° C. andthe internal pressure of the reaction chamber may be in a range of from10 Pa to 100 Pa.

[Effects of the First Embodiment]

According to the present embodiment, the first substrate and the secondsubstrate are used. The second substrate is arranged immediately abovethe first substrate. The rear surface of the second substrate is formedof an insulation film (SiN or SiO₂). In this state, at least a silane(SiH₄) gas and a hydrogen chloride (HCl) gas are supplied between thefirst substrate and the second substrate. As a result, a silicon (Si)film is allowed to selectively grow on the Si region of the frontsurface of the first substrate, and at this time, the migration ofsilicon (Si) is suppressed by the chlorine (Cl) components contained inthe hydrogen chloride (HCl) gas. Accordingly, it is possible to form asilicon (Si) film with a flat surface in a reliable manner.

In the first embodiment described above, the insulator surface of thesecond substrate is exposed toward the opposing surface of the firstsubstrate. In this configuration, the rear surface of the firstsubstrate, i.e., the product wafer, may be formed of SiN or SiO₂.However, if a Si-based film is exposed on the rear surface of theproduct wafer, the opposing surface of the product wafer, which isarranged immediately above the rear surface of the product wafer, needsto be formed of an insulation film of SiN or SiO₂.

Second Embodiment

The following is a description on certain methods (first to thirdmethods) of forming a substrate surface opposing the product Si waferwith an insulation film as according to a second embodiment.

(First Method)

In this method, the first substrates and the second substrates aredifferent types of substrates (see FIG. 3). Only the second substratesare subjected to insulation film formation processing in advance so thatthe opposing surface of each of the second substrates has an insulatorsurface.

In case where the respective dummy Si wafers (sandwiching dummy wafers)132 each having a SiN film or a SiO₂ film formed as a insulator surfaceare arranged immediately above the corresponding product Si wafers 131,the boat 105 holding the dummy Si wafers 132 stacked one above anotherat a pitch twice as great as a normal pitch is loaded into the reactionfurnace 100. Prior to loading the product Si wafers 131, a source gas issupplied to form insulation films such as SiN films or SiO₂ films on thefront and rear surfaces of the respective dummy Si wafers 132 includingthe opposing surfaces. Thereafter, the boat 105 is taken out from thereaction furnace 100. Subsequently, the product Si wafers 131 areinserted between the dummy Si wafers 132 held by the boat 105. The boat105 is loaded into the reaction furnace 100 once again to performselective growth of silicon-containing films on the product Si wafers131. According to this method, the reaction furnace with the sameconfiguration as the furnace for formation of silicon-containing filmsis used to form the insulation films. This makes it possible to reliablyform insulation films on the surfaces of the dummy Si wafers opposing tothe product Si wafers.

(Second Method)

This method is the same as the first method in that the first substratesand the second substrates are different types of substrates, but differsfrom the first method in that the opposing surfaces of the secondsubstrates are formed of insulator surfaces by subjecting the reactiontube accommodating the second substrates to insulation film formationprocessing in advance.

In particular, the boats each holding the dummy Si wafers stacked oneabove another at a pitch twice as great as a normal pitch are loadedinto the respective reaction tube in advance. The boat and the dummy Siwafers loaded into the reaction tube is coated with insulation filmssuch as SiN films or SiO₂ films. Thereafter, the boat is taken out fromthe reaction tube. Subsequently, the product Si wafers are insertedbetween the dummy Si wafers held by the boat. The boat is loaded intothe reaction tube once again to perform selective growth ofsilicon-containing films on the product Si wafers.

According to this method, the insulation films are coated not only onthe dummy Si wafers but also the boat and the reaction tube. This makesit easy to perform the film coating process as compared with the firstmethod in which only the dummy Si wafers are coated with the insulationfilms. Inasmuch as the insulator surfaces are exposed not only in thedummy Si wafers arranged immediately above the product Si wafers butalso in the members arranged around the product Si wafers, it ispossible to surely suppress the migration of silicon (Si) and toselectively form, within the reaction chamber, a silicon-containing filmwith a flat surface on the semiconductor region of the first substratein a reliable manner.

(Third Method)

In this method, the same type of the product Si wafers are used aseither of the first substrate and the second substrate. The frontsurface of each of the product Si wafers of the same type is formed tohave a semiconductor region and the rear surface thereof is formed tohave an insulation film. To this end, the third method includes:providing a plurality of product Si wafers, the front surface of each ofthe product Si wafers having insulator regions and a semiconductorregion arranged between the insulator regions, at least thesemiconductor region of the front surface being covered with an oxidefilm, the rear surface of each of the product Si wafers being coveredwith an oxide film; removing the oxide film formed on the semiconductorregion of the front surface of each of the product Si wafers whilekeeping intact the oxide film formed on the rear surface of each of theproduct Si wafers; and conveying the product Si wafers, in which theoxide film formed on the semiconductor region is removed with the oxidefilm formed on the rear surface remaining intact, into a reactionchamber in a state that the product Si wafers are stacked one aboveanother at a predetermined interval.

According to this method, the opposing surface of a substrate (e.g., arear surface of a upper product Si wafer opposing a front surface of alower product Si wafer) can be formed to have an insulation film bykeeping intact the oxide film formed on the rear surface of each of theproduct Si wafers. Since the product Si wafers in which the oxide filmformed on the rear surface remains intact are stacked one above anotherin the boat, it is possible to form, within the reaction chamber,silicon-containing films on the semiconductor regions of a plurality ofsubstrates (e.g., product Si wafers) at one time.

In the oxide film removing operation mentioned above, water may besupplied to the rear surface of each of the product Si wafers whilesupplying a hydrofluoric-acid-containing material to the front surfaceof each of the product Si wafers, in order to remove the oxide filmformed on the semiconductor region of the front surface while keepingintact the oxide film formed on the rear surface. If water is suppliedto the rear surface while supplying the hydrofluoric-acid-containingmaterial to the front surface, it is possible to prevent thehydrofluoric-acid-containing material from flowing toward the rearsurface and thus effectively keep intact the oxide film formed on therear surface.

One process of a semiconductor device manufacturing method incorporatingthe third method mentioned above may be implemented as follows. Inparticular, the third method includes: a first step of providing aplurality of product Si wafers having front and rear surfaces with oxidefilms formed thereon and cleaning the front and rear surfaces of theproduct Si wafers with DHF (diluted hydrofluoric acid) to remove theoxide films; a second step of accommodating the product Si wafers withina reaction chamber in a state that the product Si wafers having Siregions exposed on the rear surfaces thereof are stacked one aboveanother with the front surface of each of the product Si wafers arrangedin an opposing relationship with the rear surface of the adjoiningproduct Si wafer; and a third step of heating the product Si wafersaccommodated within the reaction chamber with a heater arranged outsidethe reaction chamber, supplying a process gas into the reaction chamberfrom a process gas supply system and exhausting the process gas from thereaction chamber. In the third step, a material formed by decompositionof the process gas in a gaseous layer within the reaction chamber isadsorbed to the rear surfaces of the product Si wafers and on the Siregions of the product Si wafers, thereby causing Si-containing films toselectively grow on the Si regions.

In the film formation step mentioned above, it is possible toselectively form silicon-containing films with a flat surface on thesemiconductor regions of a plurality of substrates at one time.

More specifically, the oxide film removing step in one process of asemiconductor device manufacturing method may be implemented as follows.

Selective growth can be performed by allowing a chemical oxide film togrow on the rear surface of a product Si wafer. FIGS. 6A to 6Cschematically show an oxide film removal step of removing an oxide filmgrown on the rear surface of a product wafer. The product wafer issubjected to wet cleaning before it is loaded into a furnace of ahot-wall type vertical low-pressure CVD apparatus. At this time, theproduct wafer is cleaned by a unit-wafer-type cleaning device. Thecleaning device performs pre-treatment cleaning and then DHF cleaning.In general, a spin cleaning method is employed in which a product waferis cleaned while spinning the same.

The pre-treatment cleaning is performed in the order of SC-1 cleaning(ammonia hydrogen peroxide water cleaning: ammonia (NH₃)+hydrogenperoxide (H₂O₂)+water (H₂O)) and SC-2 cleaning (hydrochloric acidhydrogen peroxide water cleaning: hydrogen chloride (HCl)+hydrogenperoxide (H₂O₂)+water (H₂O)).

After the pre-treatment cleaning, only the front surface of the productwafer is cleaned with DHF (diluted hydrofluoric acid, HF+H₂O) in the DHFcleaning step to remove the chemical oxide film. As a result, thechemical oxide film formed on the rear surface of the product waferremains intact. At this time, deionized water continues to be suppliedto the rear surface of the product wafer in order to prevent the DHFfrom flowing toward the rear surface. Thus, the chemical oxide filmformed on the opposing surface is kept intact.

In an alternate embodiment, instead of supplying deionized water to therear surface of the product wafer, a shield plate for completelyisolating the rear surface from DHF may be employed so that DHF cannotreach the rear surface of the product wafer. In lieu of the spincleaning method mentioned above, it may be possible to employ aconveying-type cleaning method in which a product wafer is conveyed in ahorizontal direction during the cleaning step. In this case, DHF isblown toward the front surface of the product wafer and deionized wateris blown against the rear surface of the product wafer while conveyingthe product wafer, thereby preventing the DHF from reaching the rearsurface. For further details on the conveying cleaning method, referenceis made to Japanese Patent Laid-Open Publication No. 2004-8847.

As described above, by allowing the chemical oxide film to remain on therear surface of the product Si wafer, it is possible to control a filmto selectively grow on the opposing surface of the product Si wafer. Inthis case, as compared with the second method in which the sandwichingdummy wafers are used, the number of the product Si wafers that can beprocessed at one time is increased in proportion to the number of thedummy wafers omitted. For example, the number of the product Si wafersthat can be conveyed by the boat represents the number of the product Siwafers that can be processed simultaneously. This significantlyincreases the throughput. More specifically, if a boat capable ofconveying 100 wafers is used, only 50 product wafers may be processed inthe sandwiching dummy wafer method. In the present method, however, 100product wafers can be processed at one time.

In the pre-treatment cleaning performed prior to the DHF cleaning, it ispossible to implement not only the SC-1 cleaning and the SC-2 cleaningbut also ozone (O₃) cleaning or sulfuric acid hydrogen peroxide water(sulfuric acid (H₂SO₄)+hydrogen peroxide (H₂O₂)+water (H₂O)) cleaning.

Further, the pre-treatment cleaning performed prior to the DHF cleaningmay be employed not only to remove natural oxide films formed on thewafers or impurities existing within or on the natural oxide films butalso to form chemical oxide films (which is formed by actively supplyingoxide to the wafers and causing a reaction thereby) in place of thenatural oxide films with uncontrollable thickness property. However, thepre-treatment cleaning may be omitted if there is no need to removeimpurities or if formation of natural oxide films does not matter.

(Substrate Cleaning Device)

In the following, one example of a substrate cleaning device forimplementing the oxide film removal step mentioned above will bedescribed in detail. This substrate cleaning device is of a unit-wafertype. A plurality of substrates, the oxide films of which have beenremoved by the substrate cleaning device, may be conveyed to a hot-walltype vertical low-pressure CVD apparatus in which the substrates aresubjected to film formation processing.

One embodiment of a substrate cleaning device 10 is shown in FIG. 7. Thesubstrate cleaning device 10 includes a device body 12 and a cleaningchamber 14 surrounded by the device body 12. A support unit 18configured to horizontally support a substrate 16 such as asemiconductor wafer is arranged within the cleaning chamber 14. Thesupport unit 18 is connected to a rotation mechanism 20, e.g., a motor,through a rotation shaft 21. The horizontally supported substrate 16 isrotated by the rotation mechanism 20.

The periphery of the support unit 18 is surrounded by a cover 22. Aswill be described later, the cover 22 is configured to receive chemicalsolutions flying from the substrate 16 when the substrate 16 is rotatedby the support unit 18.

A first nozzle 28 and a second nozzle 30 are inserted into the cleaningchamber 14. The first nozzle 28 and the second nozzle 30 arehorizontally arranged such that the tip ends thereof extend to near thecenter of the substrate 16 supported by the support unit 18.

The first nozzle 28 is connected to a first cleaning solution supplyunit 32 configured to supply a cleaning solution made of, e.g., dilutedhydrofluoric acid (DHF), through a control valve 32 a configured tocontrol the supply of the cleaning solution. The DHF cleaning solutionis supplied from the first nozzle 28 toward the center of the substrate16.

The second nozzle 30 is connected to a second cleaning solution supplyunit 34 configured to supply, e.g., an RCA cleaning solution, through acontrol valve 34 a configured to control the supply of the RCA cleaningsolution. The RCA cleaning solution is supplied from the second nozzle30 toward the center of the substrate 16. The RCA cleaning refers to acleaning method for removing foreign materials, organic materials ormetallic contaminants by the combination of cleaning sequences of SC-1(a mixed solution of NH₄OH, H₂O₂ and H₂O), SC-2 (a mixed solution ofHCl, H₂O₂ and H₂O), diluted hydrofluoric acid (DHF) and SPM (a mixedsolution of H₂SO₄ and H₂O₂).

One ends of a first water supply unit 40 and a second water supply unit41 are connected to the first nozzle 28 and the second nozzle 30,respectively, and the other ends thereof are connected to a firstdeionized water supply unit 42 and a second deionized water supply unit36, respectively. The first water supply unit 40 and the second watersupply unit 41 are configured to supply deionized water to the innersurface of the cover 22 through the first nozzle 28 and the secondnozzle 30, respectively. Control valves 42 a and 46 a configured tocontrol the supply of deionized water are provided in the first watersupply unit 40 and the second water supply unit 41, respectively.

One or more third nozzles 54 are provided to be inserted into thecleaning chamber 14. The third nozzles 54 are obliquely inserted intothe cover 22 through the bottom portion of the device body 12 and thebottom wall of the cover 22 such that the tip ends thereof extend tonear openings 18 a defined in the bottom wall of the support unit 18.The third nozzles 54 are connected to a third deionized water supplyunit 55 through a control valve 55 a configured to control the supply ofdeionized water. Deionized water is supplied from the third nozzles 54toward the rear surface of the substrate 16 through the openings 18 adefined in the bottom wall of the support unit 18.

A drain pipe 44, through which the deionized water supplied to the cover22 is drained, is connected to the bottom wall of the cover 22. Thedrain pipe 44 extends to the outside of the device body 12 so that thedeionized water existing within the cover 22 can be drained through thedrain pipe 44.

One end of a drying gas supply pipe 46 is connected to the top portionof the device body 12. A drying gas supply unit 48 is connected to theother end of the drying gas supply pipe 46. A control valve 48 aconfigured to control the supply of a drying gas is provided in thedrying gas supply pipe 46. For example, a nitrogen (N₂) gas is used asthe drying gas. An exhaust pipe 50, through which the drying gas isexhausted, is connected to the bottom portion of the device body 12.

A controller 52 is configured by a computer and is configured to controlthe rotation of the support unit 18 driven by the rotation mechanism 20,the supply of the DHF cleaning solution through the first nozzle 28under the control of the control valve 32 a, the supply of the RCAcleaning solution through the second nozzle 30 under the control of thecontrol valve 34 a, the supply of the deionized water from the firstwater supply unit 40 and the second water supply unit 41 under thecontrol of the control valves 42 a and 36 a, the supply of the deionizedwater from the third nozzles 54 under the control of the control valve55 a, and the supply of the nitrogen (N₂) gas from the drying gas supplypipe 46 under the control of the control valve 48 a.

(Unit Wafer Cleaning Method)

Next, a unit wafer cleaning method for cleaning a substrate and removingan oxide film through the use of the aforementioned substrate cleaningdevice 10, as one process of a semiconductor device manufacturingmethod, will be described with reference to FIG. 6.

First, a single substrate 16 is conveyed into the cleaning chamber 14and is prepared on the support unit 18. The rotation of the substrate 16is performed by rotating the support unit 18, which is driven by therotation mechanism 20 through the rotation shaft 21. During rotation ofthe substrate 16, the RCA cleaning solution is supplied from the secondnozzle 30 toward the center of the substrate 16. The front and rearsurfaces of the substrate 16 are cleaned to remove the natural oxidefilms 160 formed on the front and rear surfaces of the substrate 16 (seeFIG. 6A). At this time, the RCA cleaning solution flows around thesubstrate 16 to reach the rear surface as well, consequently removingthe natural oxide film 160 formed on the rear surface. In the cleaningmethod employing the RCA cleaning solution, silicon oxide (SiO₂) filmsare formed by hydrogen peroxide (H₂O₂). Thus, chemical oxide films 168of about 10 Å in thickness are formed on the front and rear surfaces ofthe substrate 16 upon completion of the above operation (see FIG. 6B).

While the substrate 16 is being rotated, the control valve 34 a isclosed to stop the supply of the RCA cleaning solution from the secondnozzle 30, and the control valve 36 a is opened to supply the deionizedwater as rinsing water from the second nozzle 30 toward the center ofthe substrate 16, thereby washing away the RCA cleaning solutionremaining on the surfaces of the substrate 16. The deionized watersupplied to the inner surface of the cover 22 is drained to the outsidethrough the drain pipe 44 together with the residual solution.

Subsequently, while the substrate 16 is being rotated, the DHF cleaningsolution is supplied from the first nozzle 28 toward the center of thefront surface of the substrate 16 and, concurrently, the deionized wateris supplied from the third nozzles 54 to the rear surface of thesubstrate 16, thereby removing the chemical oxide film 168 formed on thesemiconductor region of the front surface while keeping intact thechemical oxide film 168 formed on the rear surface (see FIG. 6C).

Further, while the substrate 16 is being rotated, the control valve 32 ais closed to stop the supply of the DHF cleaning solution from the firstnozzle 28, and the control valve 42 a is opened to supply the deionizedwater as rinsing water toward the center of the substrate 16 through thefirst nozzle 28, thereby washing away the DHF cleaning solutionremaining on the surfaces of the substrate 16. The deionized watersupplied to the inner surface of the cover 22 is drained to the outsidethrough the drain pipe 44 together with the residual solution.

The N₂ gas as the drying gas is supplied from the drying gas supply unit48 into the cleaning chamber 14 through the drying gas supply pipe 46 tokeep the cleaning chamber 14 in a N₂ atmosphere. The substrate 16 isdried in the N₂ atmosphere. Then, the rotation of the support unit 18caused by the rotation mechanism 20 is stopped. The N₂ gas existing inthe cleaning chamber 14 is exhausted through the exhaust pipe 50.

Finally, the substrate 16 is taken out from the cleaning chamber 14 andthen conveyed to the afore-mentioned hot-wall type vertical low-pressureCVD apparatus in which the substrate 16 is subjected to such processingas selective growth of an epitaxial film thereon.

Other Embodiments

In some other embodiment, the present disclosure may be modified in manydifferent forms without departing from the scope thereof. While thesubstrate processing apparatus described in the foregoing embodiments isa hot-wall type vertical low-pressure CVD apparatus, namely a batch typevertical low-pressure CVD apparatus capable of processing a plurality ofsubstrates at one time, the present disclosure is applicable to aunit-wafer-type substrate processing apparatus.

FIG. 8 is a schematic explanation view showing a reaction furnace of aunit-wafer-type (two-wafer-type) substrate processing apparatus.

As shown in FIG. 8, a reaction tube 203 (used as a reaction furnace)made of quartz, silicon carbide or alumina includes ahorizontally-extending flat space, i.e., a reaction chamber, foraccommodating semiconductor wafers 200 (used as substrates) therein. Awafer support table 217 (used as a substrate holder) configured tosupport the semiconductor wafers 200 is provided within the reactiontube 203. A gas introduction flange 209 (used as a manifold) isair-tightly attached to the reaction tube 203. A conveying chamber (notshown) is connected to the gas introduction flange 209 through a gatevalve 244 (used as a partitioning valve). A gas introduction line 232(used as a gas supply pipe) is connected to the gas introduction flange209. An exhaust line 231 (used as an exhaust pipe) is connected to aback flange 210. A pressure control unit 242 configured to control theinternal pressure of the reaction tube 203 at a specified pressure isprovided in the exhaust line 231. A turbo-molecular pump 233 isconnected to the exhaust line 231. The inside of the reaction tube 203is kept at a high vacuum pressure by the turbo-molecular pump 233. Aflow rate control unit 241 configured to control the flow rate of a gasintroduced into the reaction tube 203 is provided in the gasintroduction line 232.

Since the reaction furnace is of a hot-wall type, an upper heater 207 aand a lower heater 207 b, both of which compose a heating unit, areprovided above and below the reaction tube 203. The upper heater 207 aand the lower heater 207 b are configured to heat the inside of thereaction tube 203 either uniformly or with a temperature gradient. Atemperature control unit 247 configured to control the temperatures ofthe upper heater 207 a and the lower heater 207 b is connected to upperheater 207 a and the lower heater 207 b. A heat insulation material 208(used as a heat insulation member) is provided to cover the upper heater207 a, the lower heater 207 b and the reaction tube 203. The internaltemperature of the reaction tube 203, the flow rate of a gas suppliedinto the reaction tube 203 and the internal pressure of the reactiontube 203 are controlled at specified temperature, flow rate andpressure, respectively, by the temperature control unit 247, the flowrate control unit 241 and a pressure control unit 242, all of which arecontrolled by a controller 249.

The method of forming a silicon (Si)-containing film through the use ofthe unit-wafer-type hot-wall reaction furnace is essentially the same asthe method of forming silicon (Si)-containing films with the reactionfurnace of the hot-wall type vertical low-pressure CVD apparatus.Therefore, no description will be made in that regard.

Hereinafter, some aspects of the present disclosure will be additionallystated.

A first aspect of the present disclosure provides a method ofmanufacturing a semiconductor device, including: a first step ofconveying a first substrate provided with an opposing surface havinginsulator regions and a semiconductor region exposed between theinsulator regions and a second substrate provided with an insulatorsurface exposed toward the opposing surface of the first substrate, intoa process chamber in a state that the second substrate is arranged in aface-to-face relationship with the opposing surface of the firstsubstrate; and a second step of selectively forming a silicon-containingfilm with a flat surface at least on the semiconductor region of theopposing surface of the first substrate by heating an inside of theprocess chamber and supplying at least a silicon-containing gas and achlorine-containing gas into the process chamber.

The second substrate may be configured such that a semiconductor regionis exposed between insulator regions on the opposite surface of thesecond substrate from the opposing surface of the first substrate, andthe second step may include selectively forming a silicon-containingfilm with a flat surface on the semiconductor region of the oppositesurface of the second substrate.

The silicon-containing gas may be at least one type of gas selected fromthe group consisting of a silane gas, a disilane gas and adichlorosilane gas, and the chlorine-containing gas may be at least onetype of gas selected from the group consisting of a chlorine gas and ahydrogen chloride gas.

The insulator regions of the first substrate and the insulator surfaceof the second substrate may be made of silicon oxide or silicon nitride,and the semiconductor region of the first substrate may be made ofsilicon.

The insulator regions may be substantially flush with the semiconductorregion.

The second step may include causing a material formed by decompositionof the silicon-containing gas and the chlorine-containing gas in agaseous layer within the process chamber to be adsorbed to at least arear surface of the second substrate and the semiconductor region of thefirst substrate.

A second aspect of the present disclosure provides a method ofmanufacturing a semiconductor device, including: providing a pluralityof substrates each provided with a front surface and a rear surface, thefront surface having insulator regions and a semiconductor regionarranged between the insulator regions, at least the semiconductorregion of the front surface being covered with an oxide film, the rearsurface being covered with an oxide film; removing the oxide film formedon the semiconductor region of the front surface while keeping intactthe oxide film formed on the rear surface; conveying the substrates, inwhich the oxide film formed on the semiconductor region is removed withthe oxide film formed on the rear surface remaining intact, into aprocess chamber in a state that the substrates are stacked one aboveanother at a predetermined interval; and selectively forming asilicon-containing film on the semiconductor region of each of thesubstrates by heating the process chamber and supplying at least asilicon-containing gas and a chlorine-containing gas into the processchamber.

The selectively forming the silicon-containing film may includeselectively forming a silicon-containing film with a flat surface on thesemiconductor region of each of the substrates.

The silicon-containing gas may be at least one type of gas selected fromthe group consisting of a silane gas, a disilane gas and adichlorosilane gas, and the chlorine-containing gas may be at least onetype of gas selected from the group consisting of a chlorine gas and ahydrogen chloride gas.

The insulator regions may be made of silicon oxide or silicon nitride,and the semiconductor region may be made of silicon.

The insulator regions may be substantially flush with the semiconductorregion.

The removing the oxide film may include supplying water to the rearsurface of each of the substrates while supplying ahydrofluoric-acid-containing material to the front surface of each ofthe substrates, to remove the oxide film formed on the semiconductorregion of the front surface while keeping intact the oxide film formedon the rear surface.

A third aspect of the present disclosure provides a substrate processingapparatus, including: a process chamber configured to accommodate andprocess a first substrate provided with an opposing surface havinginsulator regions and a semiconductor region exposed between theinsulator regions and a second substrate provided with an insulatorsurface exposed toward the opposing surface of the first substrate; afirst gas supply system configured to supply a silicon-containing gasinto the process chamber; a second gas supply system configured tosupply a chlorine-containing gas into the process chamber; a heaterconfigured to heat the first substrate and the second substrate; and acontroller configured to control the heater, the first gas supply systemand the second gas supply system such that the silicon-containing gasand the chlorine-containing gas are supplied between the first substrateand the second substrate arranged in a face-to-face relationship withthe opposing surface of the first substrate, to selectively form asilicon-containing film with a flat surface at least on thesemiconductor region of the first substrate.

A fourth aspect of the present disclosure provides a method including:conveying a substrate holder configured to hold a plurality ofsubstrates staked one above another at a predetermined interval, into aprocess chamber, each of the substrates provided with a front surfaceand a rear surface, the front surface having insulator regions and asemiconductor region exposed between the insulator regions, the rearsurface exposing an insulator surface; and forming a silicon-containingfilm on the semiconductor region of each of the substrates by heatingthe process chamber and supplying at least a silicon-containing gas anda chlorine-containing gas into the process chamber.

A fifth aspect of the present disclosure provides a method including:providing a first substrate having a semiconductor region exposedbetween insulator regions and a second substrate having an insulatorsurface opposing the first substrate; and supplying at least asilicon-containing gas and a chlorine-containing gas into at least thefirst substrate and the second substrate, thereby selectively forming asilicon-containing film with a flat surface on at least thesemiconductor region of the first substrate.

According to the present disclosure, it is possible to selectively forma silicon-containing film with a flat surface on a semiconductor regionof a substrate in a reliable manner.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the novel methods and apparatusesdescribed herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe embodiments described herein may be made without departing from thespirit of the disclosures. The accompanying claims and their equivalentsare intended to cover such forms or modifications as would fall withinthe scope and spirit of the disclosures.

What is claimed is:
 1. A substrate processing apparatus, comprising: aprocess chamber configured to accommodate and process a first substrateprovided with an opposing surface having insulator regions and asemiconductor region exposed between the insulator regions and a secondsubstrate provided with an insulator surface exposed toward the opposingsurface of the first substrate; a first gas supply system configured tosupply a silicon-containing gas into the process chamber; a second gassupply system configured to supply a chlorine-containing gas into theprocess chamber; a heater configured to heat the first substrate and thesecond substrate; and a controller configured to control the heater, thefirst gas supply system and the second gas supply system such that thesilicon-containing gas and the chlorine-containing gas are suppliedbetween the first substrate and the second substrate, the secondsubstrate arranged to face the opposing surface of the first substrate,to selectively form a silicon-containing film with a flat surface atleast on the semiconductor region of the first substrate.